The standard deviation of packets per second received from a liquidity source are directly related to the number of quotes per second, or the number of trades per second occurring on that liquidity source. Thus, the higher the number of network / data packets per second, the more volatility there will be on that specific venue, or the market as a whole. std(PPS) can be used as a leading indicator of volatility in a sub-second trading environment.

This answer is based on my personal experience of analyzing multiple liquidity providers (data sources) in real-time to predict / mitigate volatility or stressed markets.